[ALUG] Help me to help someone!

[samwise]

What file system is the new disk formatted to?

If it's NTFS (which is more than likely, if it's a modern external USB
drive), ubuntu will only mount the disk as read-only because it
doesn't yet fully support writing to NTFS out of the box.

It is possible to try out the latest NTFS-3G release.  Here's a
tutorial for ubuntu edgy eft:

http://howtoforge.org/ubuntu_edgy_eft_ntfs_ntfs_3g

In my experience it's mostly stable, but v. slow.

Peter.